You can grow summer radishes early and in partial shade. Many varieties are ready to eat in 30 days. Sprinkle the seeds 1/2 inch apart in a container of your choice, and cover with a light dusting of soil (about 1/4 to 1/2 inch). Pat lightly and keep moist. Pick and eat radishes young, before they get bitter. Put them in the ground near another plant, since they help keep soil loose.